Almost a year after it started selling laptops and desktop PCs pre-loaded with Ubuntu Linux, Dell is to expand its fledgling programme to new models and markets.

In interviews at Dell's Parmer campus north of Austin last week, four Dell representatives said sales of the Linux-loaded machines had been encouraging.

Though they declined to give sales figures for the Linux-equipped machines, the officials were adamant in saying that the programme wouldn't be continuing or adding new models if the sales figures had not been adequate.

"A [sales] number is not going to validate it as much as our actions to date," which include adding new models and configurations, said company spokeswoman Anne Camden.

Dell first offered Linux on Dell machines in 1999, when Dell installed Red Hat Linux on a selection of Dell servers, said Matt Domsch, the company's Linux technology strategist in the CTO's office. A short time later, Dell tried selling consumer-focused laptops with Red Hat Linux but the effort was not sustained due to inadequate demand.

Dell has continued to sell enterprise servers with Linux since that 1999 debut, he said. The recent Linux on Dell programme for laptops and desktop machines, however, has been gaining momentum, he said. "If the programme wasn't successful, we wouldn't be able to continue it," Domsch said.

The machines can be configured and ordered at the company's Dell and Linux web page. In January, Dell announced another Linux-loaded laptop machine, with a host of high-performance features.

The Linux on Dell idea was born in February 2007 after CEO Michael Dell debuted a new company-hosted blog called IdeaStorm, where customer could provide ideas and input on prospective new products and services. More than 100,000 people posted comments about wanting to see the company sell computers with Linux preloaded, straight from the factory.

Ten weeks later, in May of last year, Dell announced it would begin selling Linux-loaded machines to consumers and businesses.

So far, Dell hasn't advertised Linux on its machines in consumer advertising campaigns, but is relying on open source enthusiasts seeking out the machines on the Dell site. Those are often the same people who suggested the combination in the first place.